<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    #d1{
      width: 100px;height: 100px;border: 1px solid red;
        /*单独某个方向设置外边距 margin-left/right/top/bottom*/
        /*margin-bottom：100px;*/
        /*四个方向赋值*/
        /*margin:50px;*/
        /*上下和左右赋值*/
        /*margin:50px 100px*/
        /*上右下左 顺时针赋值*/
        /*margin:10px 20px 30px 40px;*/
      margin-bottom: 50px;
    }
    body{margin: 0}/*去掉body自带的8个像素外边距*/
    #d2{
      width: 100px;height: 100px;border: 1px solid red;
        /*上下相邻彼此添加外边距 取最大值*/
        margin-top: 100px;
    }
    #s1{
        /*行内元素上下外边框无效*/
        /*margin-bottom: 100px;*/
        margin-right: 100px;
    }
    #s2{
        /*左右相邻彼此添加外边距 两者想加*/
        margin-left: 50px;
    }
    #big{
        width: 200px;
        height: 200px;
        background-color: red;
        overflow: hidden;/*解决粘连问题*/
    }
    #big>div{
        width: 50px;
        height: 50px;
        background-color: green;
        margin-left: 50px;
        /*当元素的上边缘和上级元素的上边缘重叠时，给元素添加上外边距会出现粘连问题，给
        上级元素添加overflow:hidden样式解决*/
        margin-top: 50px;
    }
  </style>
</head>
<body>
<div id="big">
    <div></div>
</div>
<span id="s1">span1</span><span id="s2">span2</span>
<div id="d1"></div>
<div id="d2"></div>

</body>
</html>